Mercury-tube switch



y 1930- 1. EfM cABE 1,757,436

MERCURY TUBE SWITCH Filed Dec. 5, 1927 IN VEN TOR.

IRA z MQCABE 9 WWJ M ATTORNEYS.

Patented May 6, 1930 PATENT OFFICE ma in. means, or oarcaeo, ILLmoIs MERCURY-TUBE SWITCH Application filed December 5, 1927. Serial No. 237,632.

This invention relates to improvements in electric switches of the type commercially known as mercury tube switches.

It is an Object of this invention to provide a mercury tube switch the construction of which is simple, inexpensive, readily manufactured by machinery, producing a mercury to mercury contact between the terminals and which is positive in its action and is of indefi nite life as long as the tube remains whole.

With these and other objects in view reference is made to the accompanying drawing for a fuller understanding of this invention. While a preferred form isillustrated upon the drawing, it is to be understood that minor detail changes may be made without departing from the scope of the invention.

In the drawing:

Figure 1 is a view in central longitudinal horizontal section of a preferred form of this invention looking downward, as on line 11 of Figure 2.

Figure 2 is a view in central longitudinal vertical section taken on the line 2-2 Figure 1.

Figure 3 is aview in side elevation illustrating the position of the mercury when the tube is tilted to closed position in full lines, and in dotted lines when tilted to open position.

Figure 4 is a view in transverse vertical section taken on the line 4+4: of Figure 2.

Electric switches of this type are customarily formed of a tube of glass closed at each end with the two terminals of the circuit to be controlled thereby projecting through and sealed in the walls thereof, the air exhausted and replaced by some gas to reduce arcing and containing a suflicient amount of an electrically-conducting fluid, such as mercury, to flow from end to end as the tube is tilted to make or break an electric contact between the interiorly projectingterminals. This type of switch has become known in the art as a mercury tube switch, as mercury is customarily employed as the electrical conducting fluid within the tube for making and breaking the electrical contact. I

In carryin out this invention, the tube 1 o is of glass 0 cylindrical form tapered to a closure at one end with the lead-in wires 2 and 3 passing through the otherend, the walls thereabout being brought together, as shown, to close the tube and support the lead-in wires in such closure. These lead-in wires may be of any electrical conducting material suitable for sealing in glass and if the material is also such as not affected by contact with the electrical conducting fluid 4, they may be projected within the interior of the tube to form the terminals of the electric circuit to be controlled. If the lead-in wires do not possess this quality, the terminals of the desired character are secured to the lead-in wires, as by Welding just before they leave the glass seal to pro ect into the interior of the tube.

It is customary to arrange the terminals of mercury tube switches in a vertical plane, with the lead-in wires entering the tube above or below the center line, so that by rotating the tube about its vertical center in. atilting motion, the electrical conducting fluid wlll flow from one end to the other and close or break the electrical contact between the terminals. This invention contemplates arranging the lead-in wires 2 and 3 one above the other in spaced relation entering through the sealed glass end in a vertical plane. The upper terminal 5 is formed from the lead-in wire 2 above the central horizontal plane of the tube or is a continuation formed of a desired material and secured thereto, as above described, and projects a short distance with the interior of the tube and is then bent downward, preferably at right angles to the honzontal and terminated short of the bottom of a cup 6 adapted to contain a portion oi the electrical conducting fluid. This cup 6 is of any desired insulating mater1al, such as isolantite which is readily shaped by mold- 'ing or machining. It is of such size as to be readily inserted into the tube before sealing the lead-in wires therein, and preferably of less depth than the interior radlus of the tube, although it may be of greater depth if desired. The upper edges of the cup are flanged outward and the on is preferably grooved about its outer sur ace just below the outwardly extend ng flanged top. The

other terminal 7 or one arranged below the horizontal center of the tube, rojects with-.

in the tube and then embraces t e cup 6 preferably engaging the outer surface thereof within the groove just belowthe outwardly flanged upper edge whereby it is securely supported in proper relation to be out of contact with the end of the upper terminal 5 as well as out of contact with the inner walls of the tube. The terminals 5 and7 are separated from each other by the walls of the cup of insulating material at all times during the normal operation of the switch.

When the tube is first tilted to the normal position to close the circuit, the conduct ng fluid will flow toward the end supporting the terminals, contact with the lower terminal, enter and fill the cup and the flu1d entering the cup will embrace and contact the upper terminal and, when tilted in the opposite direction to the normal position to break the circuit, the conducting fiuld Wlll flow to the opposite end but suflicient fluid will remain in the cup to submerge the lower end of the upper terminal so that thereafter during break the circuit,- the make or break will occur when the main body of conducting fluid embracing the lower terminal contacts or departs from the smaller body contained within the cup embracing the upper terminal,

-whereby the circuit is closed or broken through the contact or separation of the two bodies of the conducting fluid.-

It is preferable to impart a downward bend to the lower terminal 7 as it leaves its engagement with the cup 6, as shown, so that the cup is slightly tilted in the direction of the opposite end to facilitate the entry and de arture of the main body of conducting fluid as the tube is tilted in its normal operation.

This construction readilylends itself to the formationof such switches by mechanical means or machinery-while heretofore it has been customary to make mercury .tube

. switches by hand which has required employment of skilled artisans In carrying out this invention, the tube 1 is of stock size glass tubing out the proper length, the cup is molded or otherwise formed, the lead-in wires with extending terminals are first bent,

one to engage and secure the cup and the other with the angular extremity of the proper length,and then held by their .remote ends in a vise, or other support, in proper relation to each other, the open end of the tube advanced to receive with the tube the cup and other terminal and then the walls of the open end are brought together, sealing and supporting the lead-in wires and terminals: in proper relation. The air within the tube may be exhausted and any desired gas may be substituted as the end opposite "the terminals is sealed.

the normal movement to make or conducting fluid with two electric terminals sealed and supported in the walls thereof, and

a cup of insulating material therein su ported at an angle to the axis ofthe tube y one terminal so that the cup is slightly tilted in the direction of the opposite end with the other terminal entering the interior of said cup.

2. A liquid contact switch comprisin a sealed'tube containing a quantity of electrical conducting fluid wit sealed and sup orted one above the; other in one end thereo? and a cup of insulating material therein supported by one terminal with the other terminal entering the interior of said cup. 7 v

3. A liquid contact switch comprising a sealed tube containing a quantity of electrlcal contacting fluid with lead-in wires supported and sealedin one end thereof, said lead-in wires projecting as terminals within the tube,

a cup of insulating material engaged by one terminal and supporter at an angle to the axis of the tube thereby so that the cup is slightly tilted in the direction of.the opposite end free from contact with the tube and separating said terminal from the other terminal, said other terminal entering free from contact into said cup.

4. A liquid contact switch comprisin a sealed tube containing a quantity of electrical conducting fluid with two electric terminals sealed and supported in the walls thereof,

two electric terminals and a cup of insulating material therein sup- 1 ported by one terminal with the other terminal entering the interior of said cup, said cup adapted to normally retain a portion of the conducting fluid'therein and sup orted with its open top at an angle to the ength of the tube so that the cup is slightly tilted in the direction of the opposite end, whereby upon tilting of the tube longitudinally the main body of the said fluid readily entersthe cup to close the circuit between the terminals or departs from the cup to open said circuit. '5. A liquid contact switch comprisin a sealed tube containing a quantity of electrical conducting fluid with two electric terminals,

sealed and supported one above the other in one end thereof, and a cup of insulating material therein embraced by the lower terminal with the upper terminal entering the interior of the cup. i

6. A liquid contact switch comprising a sealed tube containing a quantity of electrical conducting fluid with two electric terminals sealed and supported'one above the other in one end'thereof, a cup of insulating material within the tube, the lower terminal bent at an angle to the axis of the tube and then about the cup to embrace its body and support its top opening in the direction or ,the opposite end of the tube and the upper terminal bent downwardsto enter within the cup and be insulated from the other terminal except when the tube is tilted to cause the conducting fluid t0 flow into the cup and complete an electrical connection between the two terminals.

Signed at Chicago, Illinois, this 2nd day of December, 1927. v

I IRA E. MOCABE. 

